Add KVM support for CI testing

[JayAndJef]

Problem

GitHub's hosted runners do not support nested virtualization or KVM acceleration. Our kernel tests require:

• KVM acceleration (-enable-kvm)
• x2apic support (-cpu host,+x2apic)
• Hardware acceleration (-machine q35,accel=kvm)

Software emulation cannot provide x2apic support, so we need actual KVM acceleration.

Solution

This PR implements comprehensive documentation and preparation for KVM-dependent CI testing:

📚 Documentation Added

• docs/CI_KVM_SETUP.md: Complete guide covering all KVM CI solutions
• Updated README.md: Testing requirements and CI information

🎯 Recommended Solutions Documented

1. Actuated Runners (Primary recommendation)

   • Drop-in replacement for GitHub hosted runners
   • Secure isolated VMs with KVM support
   • Professional service with support

2. Self-Hosted Runners (Alternative)

   • Complete setup instructions provided
   • Full control over environment
   • Cost-effective for high usage

3. Manual Testing Workflows (For verification)

   • Comprehensive KVM system diagnostics
   • Multiple runner type support
   • Detailed verification steps

Changes in This PR

• docs/CI_KVM_SETUP.md: Detailed documentation of all KVM CI solutions
• README.md: Updated with testing requirements and CI information

Workflow Files (To Be Added Separately)

Due to GitHub workflow permissions, the actual workflow files will need to be added in a follow-up commit:

• Updated main workflow for Actuated runners
• Manual KVM testing workflow
• Self-hosted runner workflow

Next Steps

1. Merge this PR to add documentation
2. Choose CI solution:
   • For Actuated: Sign up at actuated.com
   • For Self-hosted: Follow setup guide in docs
3. Add workflow files with appropriate permissions
4. Test setup using manual workflows

Benefits

✅ Comprehensive documentation for all KVM CI options
✅ Clear setup instructions for each solution
✅ Security considerations and recommendations
✅ Preparation for automated x2apic-dependent kernel testing
✅ Multiple solution paths to fit different needs

This PR lays the groundwork for solving the KVM CI testing challenge while providing flexibility in implementation approach.

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Pull Request opened by Augment Code with guidance from the PR author